What type and class of fire extinguishers are there

Fire extinguishers are classified by the type of fire they are designed to extinguish. The main classes are A, B, C, D, and K. Each class addresses a specific type of combustible material. [1] [2]

Class A extinguishers are for ordinary combustibles such as wood, paper, and cloth. They work by cooling and quenching the burning materials. [8]

Class B extinguishers are for flammable liquids like gasoline, oil, and grease, and they work by smothering the fire. [8]

Class C extinguishers are for energized electrical equipment. The extinguishing agent must be nonconductive. [8]

Class D extinguishers are for combustible metals like magnesium and titanium. They use a coarse powder to seal and smother the fire. [8]

Class K extinguishers are designed for cooking oils and fats and are typically found in commercial kitchens. [1]

Common types of fire extinguishers include:

• Water extinguishers for Class A fires, which remove heat from burning materials.
• Carbon Dioxide (CO₂) extinguishers for Class B and C fires, which displace oxygen.
• Dry Chemical extinguishers, which can be marked for multiple classes (e.g., ABC) and work by creating a barrier between fuel and oxygen.
• Wet Chemical extinguishers for Class K fires, which prevent re-ignition. [3] [3] [3] [5]

Regulatory standards require extinguishers to be:

• Conspicuous and clearly visible.
• Readily accessible and not obstructed.
• Located along normal paths of travel and exits.
• Inspected monthly and maintained annually. [2] [2] [2] [2]

Travel distance to extinguishers should not exceed 75 feet for Class A and D fires, and 50 feet for Class B fires. Class K extinguishers should be within 30 feet of the hazard. [2] [2] [7]

OSHA mandates that employers provide portable fire extinguishers, ensuring they are readily accessible and properly maintained. Extinguishers using carbon tetrachloride or chlorobromomethane are prohibited. [7] [7]

Regular inspections and maintenance are essential, including monthly visual checks and annual inspections by certified personnel. [6] [2]

Employees should be trained on fire extinguisher use, including the PASS method (Pull, Aim, Squeeze, Sweep). [4] [9]

Using the wrong type of extinguisher can be dangerous; for example, water should not be used on electrical or flammable liquid fires. [4]

When in doubt about fighting a fire, evacuate, sound the alarm, and call the fire department. [1]

Fire extinguishers should be approved by a nationally recognized testing laboratory. [7]

In locations where visual obstructions exist, signs should indicate the extinguisher's location. [7]

Fire extinguishers should be installed on hangers or brackets, not placed on the floor. [2]